Mini-conference 2019

WELCOME

On behalf of the partners of The D’Entrecasteaux and Huon Collaboration, hosted by NRM South, we welcome you to the ‘Our Waterway’ mini conference, 2019. The program features a broad range of talks looking at waterway condition, biodiversity and management strategies.

Our sincere thanks go to all the speakers for providing us with new information and expanding our understanding of the D’Entrecasteaux and Huon waterways. This new information will impact in how we consider and address waterway issues and opportunities into the future.

We also thank all the rope weavers who kindly provided the artwork on display. Marine debris has been an important focus for The D’Entrecasteaux and Huon Collaboration. Sharing these works helps us remember the impacts of marine debris in the ecosystem and generate awareness and discussion in the community.

Dr Amelia Fowles

The D’Entrecasteaux and Huon Collaboration Coordinator, NRM South

CONFERENCE TIMETABLE

9:30 AM

WELCOME

9:40 AM

Our Waterways: The D’Entrecasteaux and Huon (Amelia Fowles), and the Derwent (Sam Whitehead)

9:50 AM

Tinderbox and Ninepin Point Marine Reserves. Lessons for conservation and fishery management from monitoring programs spanning 27 years of protection (Neville Barrett)

10:10 AM

The salmon industry, science and technology – a pathway to the future (Sean Riley, Tassal)

SPEAKER ABSTRACTS

INTRODUCTORY TALKS

Dr Amelia Fowles is The D’Entrecasteaux and Huon Collaboration Coordinator at NRM South. Amelia’s role involves planning and implementation of The D’Entrecasteaux and Huon Collaboration, and coordinating projects that raise awareness, improve practices and build a common understanding of the environmental issues associated with regional coastal, estuarine, freshwater and marine values. She has a PhD from the University of Tasmania and has worked in a range of sectors including research and environmental management.

Sam Whitehead is an estuarine scientist with twelve years of local and international experience within the construction, energy, transportation, oil and gas, government and not for profit sectors. Since joining the Derwent Estuary Program in 2013, Sam has specialised in water quality data analysis, habitat condition assessment, stakeholder engagement, technical reporting and database management.

Abstract

The D’Entrecasteaux & Huon Collaboration was formed in 2013 due to combined community, industry and government interest in the region. The Derwent Estuary Program (DEP) began in 1996 with a review of nutrient loads and grew to become a stable and diverse program aiming to deliver “science for management”. The Collaboration and DEP recognise that the Derwent, D’Entrecasteaux and Huon waterways are connected systems, and that the regions share a number of values, stakeholders and ecological stressors. Amelia Fowles (D’Entrecasteaux & Huon Collaboration) and Sam Whitehead (Derwent Estuary Program) will focus on the collaborative structure that underpins both the D’Entrecasteaux & Huon Collaboration and the Derwent Estuary Program. We highlight this collaborative model as one approach to the goal of optimal management of a shared waterway.

Tinderbox and Ninepin Point Marine Reserves: Lessons for conservation and fishery management from monitoring programs spanning 27 years of protection

Neville Barrett, IMAS

Speaker Profile

Naughty Neville is a marine ecologist based at IMAS, University of Tasmania. He has over 30 years of experience in research on Tasmania’s coastal and offshore ecosystems, with a significant focus of reef fish biology, rocky reef ecology, and using marine protected areas (MPAs) to understand variability in our coastal species and the extent that human activities or natural environmental processes influence this. Along with his colleague, Prof Graham Edgar, he has been actively monitoring changes in all of Tasmania’s marine reserves since their inception and todays’ talk will focus on lessons learnt from reserves in the D’Entrecasteaux and Huon regions.

Abstract

Two no-take marine reserves sit within the D’Entrecasteaux and Huon waterways, one at Tinderbox and one at Ninepin Point. These were established in September 1991 and protect representative examples of habitats and species within these estuarine systems. Monitoring of both these reserves commenced in 1992 and has continued annually (where funding was available) in most years since. The monitoring is broadly-based and follows patterns in a wide range of reef-associated species, including seaweeds, mobile macro-invertebrates (e.g. seastars, sea urchins, lobsters, abalone) and fishes. The results document both the remarkable long-term stability of many species, including dominant seaweeds, but also the loss of some previously common species in response to broad-scale environmental change, and a number of significant changes in response to protection from fishing. This presentation will discuss the implications of our findings for both conservation and fishery management.

The salmon industry, science and technology – a pathway to the future

Sean Riley, Tassal

Speaker Profile

Sean Riley is an experienced natural resource manager with over 25 years of experience in marine science, fisheries and forestry management, and in 2013 was appointed to the Tasmanian Natural Resources Management Council. Sean has been project manager for the Broadscale Environmental Monitoring Program (BEMP) and now works for Tassal.

Abstract

The Tasmanian salmonid industry has been fortunate to benefit from a range of scientific programs delivered by such organisations as IMAS and the CSIRO. The FRDC too has played a significant role in supporting collaborative industry research programs that have improved the industry’s performance across a range of fish health, social and environmental outcomes. New modelling platforms developed by the CSIRO are leading the way in allowing us to better understand the environmental response from nutrient inputs into the D’Entrecasteaux Channel and Huon Estuary. Understanding and measuring the environmental impacts of salmonid aquaculture is a key focus of industry. The Broadscale Environmental Monitoring Program (BEMP) has reached a 10 year milestone and comprises a world-class data set on water quality and sediment condition – and ultimately ecosystem structure and function within the D’Entrecasteaux Channel and Huon Estuary. This is important for The D’Entrecasteaux and Huon Collaboration managed through NRM South. The development of new technologies (such as real-time sensor units) will pave the way for industry, resource managers and regulators to more effectively manage environmental change in these important waterways – as that change is occurring. The advent of the CRC for the Blue Economy also provides a platform for more rapid development and adoption of new innovations and technologies to establish Tasmania as a world leader in sustainable finfish aquaculture.

Harmful algal blooms in the Huon and D’Entrecasteaux region

Gustaaf Hallegraeff, IMAS

Speaker Profile

Gustaaf Hallegraeff is a Professor at the University of Tasmania’s Institute for Marine and Antarctic Studies. He is recognised internationally for his marine biosecurity work on harmful algal blooms impacting on human health, the fish farm and shellfish industries, their stimulation by coastal eutrophication, responses to climate change and global spreading via ship’s ballast water.

Abstract

Various microalgal blooms in the Huon Estuary and D’Entrecasteaux Channel have attracted public attention over the past 30 years. Toxic dinoflagellate blooms of Gymnodinium catenatum at times have generated dangerous levels of paralytic shellfish toxins in shellfish, notably in 1986, 1991 and 1993. This has caused significant hardship for the local mussel and oyster industries which repeatedly suffered lengthy farm closures. This problem has since been largely solved by no longer allowing any shellfish culture leases within the Huon estuary proper. Recreational collection of wild shellfish however has occasionally continued to be responsible for human poisonings and even hospitalisations. Different species of microalgae occasionally have caused problems from the salmon industry. All algal blooms at high concentrations (millions of cells/L), e.g. by the nontoxic dinoflagellate Tripos fusus, can irritate fish gills. Pink slicks of the large non-toxic dinoflagellate Noctilucaspp. have become a common phenomenon since the 2000s, have sometimes been mistaken for pollution, but also attracted tourists because of their spectacular night-time bioluminescence. Diatom blooms of the cold-water Chaetoceros criophilum and Ch. danicus have repeatedly caused gill damage to salmon in NW Bay even at very low cell concentrations. Increasing incursions of tropical dinoflagellates, e.g. Tripos gravidus, are being observed in Storm Bay, carried in by the Leeuwin Current in winter or East Australian Current in summer.

NUTRIENTS, REEFS, FISH FARMING AND MANAGEMENT

Monitoring rocky reefs for the effects of organic enrichment using rapid visual assessment

Camille White, IMAS

Researcher Profile

Dr Camille White is a Research Fellow at the Institute for Marine and Antarctic Studies, University of Tasmania. She is interested in aquaculture environment interactions, in particular how marine food webs assimilate and respond to organic enrichment. Her work focuses on interactions between salmon farming and temperate reef ecosystems, along with trophic links and uptake of marine farm nutrients in the water column.

Speaker Profile

Associate Professor Catriona Macleod is Deputy Head of the Fisheries and Aquaculture Centre within IMAS, and a senior research fellow with specific expertise in environmental impact assessment. A key research focus has been improving understanding of the environmental impacts and interactions of finfish aquaculture, and in providing the system understanding and recommendations to support sustainable development and management of aquaculture operations. She also has an interest in heavy metal contamination and how management actions in coastal/ estuarine systems can influence the impacts of metals, both in terms of bioavailability and ecotoxicity.

Abstract

As the aquaculture industry expands, there is a need for a standardised approach to monitoring the health of key habitats, including Tasmania’s iconic reef ecosystems. Along with high intrinsic conservational value, temperate reefs in Tasmania support valuable commercial fisheries, such as rock lobster and abalone, with growing concern regarding the interaction between aquaculture and these ecosystems. Through a large Fisheries Research and Development Corporation (FRDC) project, we developed a rapid visual assessment (RVA) technique targeted to detect potential loss of resilience and function on rocky reefs due to stress from organic enrichment. The challenge was in developing a technique rapid enough to be undertaken on a regular basis, but powerful enough to detect changes on rocky reefs that could be specifically attributed to organic enrichment. Fourteen key response parameters were identified and tested. These response parameters were mainly derived from four functional categories, and included canopy and sub-canopy cover, turfing algae and substrate composition, cover of rapid growth algae including ephemeral and epiphytic species, and levels of primary consumers. This method was tested in the southern D’Entrecasteaux Channel, with method refinement occurring throughout this period. It was found that this method could be used to detect a spatial gradient of organic enrichment in the lower Channel, however, temporal validation can only be done over a longer (5+ years) time series of data. Through the RVA approach we have developed what could be an important tool to assist with the monitoring and management of the impacts of salmon farming on temperate rocky reefs.

Storm Bay science: The past, present and future

Jeff Ross, IMAS

Speaker Profile

Dr Jeff Ross is a Senior Research Fellow at the Institute for Marine and Antarctic Studies, University of Tasmania. He works in the Fisheries and Aquaculture Centre that conducts research to support the long-term sustainability of fisheries and aquaculture in Tasmania. His work focuses on understanding the environmental impacts and interactions of finfish aquaculture in Tasmania.

Abstract

Storm Bay is identified in the Tasmanian Government’s Sustainable Industry Growth Plan for the Salmon Industry as a priority area for the possible expansion of salmonid marine farming. Several developments have now been approved. There has been much conjecture on the amount of science available on Storm Bay to support the decision-making process. This talk provides a snapshot of previous studies, describes current research and outlines the planned monitoring program and habitat mapping.

Storm Bay Modelling and Information System

Karen Wild-Allen, CSIRO

Speaker Profile

Karen Wild-Allen is a Principal Research Scientist and biogeochemical modeller in the CSIRO Oceans & Atmosphere Coastal Environmental Modelling team. She is an established leader in assessment of the environmental impacts of salmon farming and has applied models to quantify and characterise the environmental impacts of anthropogenic loads to coast and shelf scale systems in Tasmania and Chile. Karen has authored 36 papers and 2 book chapters (696 citations; Web of Science H-index 11).

Abstract

The Storm Bay Modelling and Information System builds on previous CSIRO initiatives in Southeast Tasmania (pilot models and decision support tools developed for limited areas in the INFORMD projects 2008-17) to deliver near real time and short-term forecasts of water circulation, water quality (e.g. temperature, salinity, nutrient, oxygen and algal content), and plausible future conditions under alternate management scenarios, demonstrated in detail throughout Storm Bay. New observations with high spatial and/or temporal resolution are being collected to inform the model and assess its performance. Observations include autonomous glider cross shelf transects to characterise the influence of the Zeehan Current, the East Australia Current and Southern Ocean water on the ventilation of Storm Bay. Benthic landers have also been deployed to assess the role of wave and storm induced resuspension on nutrient supply in the Bay. Over the next 3 years, the Storm Bay Modelling and Information System will be developed to provide the foundational capability to deploy local water quality models in multiple areas of interest, to quantify flushing, characterise water quality and explore future scenarios for expansion of the aquaculture industry, to inform resource managers.

Online decision support tools assisting environmental sustainability of aquaculture and other industries in South East Tasmania

Rebecca Gorton, CSIRO

Speaker Profile

Rebecca Gorton is a Senior Software Engineer and the Team Leader in Oceans and Atmosphere, CSIRO. Rebecca works across a broad range of scientific fields from fisheries assessment and climate change to ocean connectivity. Rebecca is passionate about enabling science by working within science teams to increase use of technologies such as high-performance computing and machine learning. She is the Project Leader of the FRDC project ‘Next generation decision support tools to support sustainable aquaculture in Storm Bay’, an exciting project that aims to deliver the systems and knowledge for ongoing science-based resource management of the Salmon Industry in Storm Bay, Tasmania.

Abstract

The sustainable development of aquaculture facilities and other industries within the Huon-D’Entrecasteaux system requires industry, regulators and the community to have ongoing access to detailed environmental information, as well the ability to evaluate the potential impact of any proposed changes in operations. Significant progress has been made in the development of environmental models and deployment of decision support systems for this region. We will describe online tools that support rapid exploration of the potential spatial effects of changes in nutrient loads and other contaminant inputs. This includes an ocean spatial connectivity modelling tool for estimating and visualising the potential spread of waterborne contaminants and pathogens; and a marine ecological emulator for rapid estimation of the impacts of marine and coastal activities on local water quality. These tools are already being utilised for management purposes and major developments are planned under current projects supported by the Fisheries Research and Development Corporation.

Dr Bernadette Proemse is an aquatic scientist interested in all facets of water quality and hydrochemistry. Following her MSc in hydrology, she completed a PhD in isotope geochemistry in Calgary, Canada, before moving to Australia. She is currently the Catchment Scientist at the Derwent Estuary Program (DEP), in addition to conducting isotope research at UTAS.

Abstract

Nutrient pollution in waterways is one of the most widespread, costly and challenging environmental problems in the world. Increasing nutrient loads, among other stressors, are changing the water quality of the River Derwent and its estuary. Preliminary data show that elevated levels of nitrogen is the key nutrient stimulating algal growth in this catchment, already causing seasonal algal pollution in the river and upper estuary. The estuary contains many sources of nitrogen, including wastewater treatment plant effluent, fish farm effluent, dairy farm, manure and fertilizers runoff, as well as stormwater runoff. These sources can be identified and quantified using isotopic fingerprinting of nitrogen. Previous research has shown that nitrogen isotopic fingerprints in macroalgae are useful bioindicators. In this study, common ulvoids along rocky reefs of the estuary foreshore were sampled and analysed for their nitrogen and carbon content, and nitrogen and carbon isotopic composition. Results show that sampled ulvoids in the lower and middle estuary predominantly use a mixture of two nitrogen sources, marine N and sewage N from waste water treatment plants. Sewage N contributions ranged from 1% near Tinderbox to 100% at Cameron Bay. This work also represents a baseline study of N sources in light of increasing fish farm developments.

FLORA, FAUNA AND BIODIVERSITY

Joe Valentine is Principal Marine scientist at Aquenal, an environmental consultancy that specialises in marine environmental monitoring. Joe has a background in marine ecology and has been managing BEMP and other aquaculture monitoring programs around Tasmania for the past 5 years.

Abstract

The Broadscale Environmental Monitoring Program (BEMP) was initiated in 2009 to provide knowledge and information on ecosystem function in the D’Entrecasteaux Channel and Huon Estuary. Participation in the BEMP is a licence requirement for finfish operators in the region and the program is funded by the Tasmanian Salmon Growers Association (TSGA). The objective of the program is to document broad scale spatial and temporal trends for key environmental parameters, allowing assessment of the environmental effects of finfish aquaculture in the region. Sampling specifications are prescribed by the EPA and include assessment of water quality and sediment health at a broad scale across the D’Entrecasteaux Channel and Huon Estuary. This presentation provides an overview and update of the BEMP program, with a focus on results from seabed sampling activities.

Species on the move: Climate-driven marine species range shifts in South East Tasmania

Barrett Wolfe, IMAS

Speaker Profile

Barrett is originally from a small fishing community on the Chesapeake Bay, United States. After pursuing studies at the University of Hawai’i and California State University’s Shark Lab, he is now a PhD student at the University of Tasmania’s Institute for Marine and Antarctic Studies. Barrett’s research focus is on marine animal behavior and physiology that can inform conservation and management in a changing world.

Abstract

South East Tasmania (including the D’Entrecasteaux Channel and Huon Estuary) has been host to a number of species either arriving or increasing in abundance as temperatures increase and water conditions change in the region. These phenomena are known as climate-driven species redistributions, or ‘range shifts’. Marine range shifts can have critical implications for biodiversity, natural resources and the coastal communities that depend on them. However, many important aspects of range shifts remain unknown. To predict range shifts and their ecological effects, we need to understand the biology of why species respond to climate change differently, and the role of newly arrived species in ecosystems. As an ocean warming hotspot, SE Tasmania provides a natural laboratory to investigate these dimensions of range shifts. My research capitalises on the ongoing range extension of the predatory fish species snapper (Chrysophrys auratus) into the region. With laboratory experiments I’ve investigated how cold may set range limits for snapper due to the response of their swimming ability and metabolism to temperature. To understand the role of species in the SE Tasmanian ecosystem, I am tracking the movements of electronically tagged snapper throughout the year and analysing their diet. This research will improve our ability to predict and manage range shifts and effects not only for snapper, but future range shifts in the region and globally. I will also give an overview of other ongoing and recent species-on-the-move focused IMAS research projects.

Dr Cayne Layton is currently a Postdoctoral Research Fellow at IMAS. He completed his PhD at IMAS studying Ecklonia radiata kelp population and community ecology. His was originally from the mainland, but now calls Tassie home.

Abstract

Kelp forests are the foundation of the Great Southern Reef, Australia’s continent-wide temperate reef system that supports high levels of biodiversity, endemism and economic value. Unfortunately, in Australia and elsewhere, kelp forests are experiencing habitat loss due to climate change, overgrazing from herbivores, and coastal development and pollution. Globally, some of the most dramatic declines have occurred in south-eastern Australia, where 95% of giant kelp (Macrocystis pyrifera) forests have disappeared in recent decades. The feasibility of ecological restoration of these underwater giants – which can reach heights above 35 m and grow 50 cm per day – is being assessed as a potential element of kelp forest conservation. We outline the key drivers of loss of Australia’s giant kelp forests – increasing water temperatures and associated reductions in coastal water nutrients – and discuss the approach to assess restoration efforts. We present novel methods to overcome and alleviate the drivers of giant kelp forest loss, including identification and selection of the most thermally tolerant genotypes/populations, acclimation to current/future conditions and intervention to minimise effects of grazers and competitors after outplanting. We also examine the genetic population structure of the remnant giant kelp patches to examine whether there is any genotypic foundation to thermal performance. Additionally, we illustrate how Integrated Multi-Trophic Aquaculture (IMTA) and permaculture may facilitate kelp growth via utilisation of the nitrogenous waste from finfish aquaculture. Finally, we discuss the broader management implications of our findings, and the potential to restore resilience to the sparse remaining giant kelp forests in Australia. The project outlined here is a necessary ‘Phase I’ of a potential larger project. It aims to assess the feasibility for future up-scaling of restoration and permaculture efforts and fill critical knowledge-gaps to provide scientific rigour and risk-management in these efforts.

Lincoln is a PhD student working on a project that primarily focuses on the comparison of species assemblages between mooring types over a temporal scale. His interests include benthic ecology, conservation biology and spatial ecology.

Abstract

With the global increase in coastal urbanisation and ocean sprawling, it will be necessary for the manager to understand the potential impacts to ensure the sustainability of the coastal system. The steady increase in boating activities will lead to a parallel rise in demand for boat storage facilities. One of the typical on-site storage methods included the use of moorings within sheltered bays. Traditional mooring design, while useful in anchoring vessels, have notable ecological concerns, including repeated mechanical disturbances to the benthic system due to chain movements. The significant impact from moorings have driven the development of environmentally sensitive (ES) mooring designs, yet currently, there is a limited number of documented ES mooring adaptations and comprehensive studies on their ecological effects. This project focuses on existing mooring fields within South East Tasmania and replaces chain moorings to ES moorings. The field experiment provides an opportunity to document technical requirements, including engineering and spatial models for the deployment of ES-mooring in a mixed field configuration. In addition, we set up a Before-After-Control-Impact (BACI) experiment to monitor the changes in species assemblages as and microhabitat features over 12 months to document the recovery potentials and potential conservation capability for spotted handfish (Brachionichthys hirsutus) following the replacement. Through a multi-disciplinary approach, this study aims to provide input for ecosystem management, including to establish if ES moorings are valid for the conservation of the B. hirsutus population.

MANAGEMENT STRATEGIES

On country to make a difference

Kath Keifer, pakana Services

Abstract

pakana Services was originally borne out of an NRM South project. pakana Services is a land management enterprise designed to change the lives of Tasmanian Aboriginals. Through successful partnerships, pakana Services has grown into a thriving business. In recent times, pakana Services have expanded into a new venture, partnering with Tasmania’s 3 largest aquaculture businesses. Focused on reducing marine debris, regular collections are building up data to underpin decision making surrounding environmental policy for aquaculture employees. It’s through such important collaborations that pakana is able to continue to close the gap for Aboriginal Tasmanians and make a difference to the environmental outcomes on country.

Kingborough’s Coastal Hazards Program

Jon Doole, Kingborough Council

Speaker Profile

Jon Doole is the Manager of Environmental Services at Kingborough Council. Jon has coordinated a program to better understand the critical issues relating to Kingborough’s extensive coastline and to develop potential response methodologies in response to the ever-increasing pressures.

Abstract

Kingborough has a lot of coastline!! It is apparent that damage of Kingborough’s coastline and the potential flooding and damage of homes and other assets is a problem currently and will only get worse into the future. So, it has been important to get a better idea of where the greatest risks and pressures to our coasts and their communities exist now and what changes to weather patterns and sea levels may mean to them in the future. From this we are able to take advice on what might be the short, medium- and longer-term responses and maybe the implications of not responding at all. We have tried to take a case study approach at the key locations such as Coningham, Kingston Beach and Nebraska Beach to better understand how bad things may get and what (if anything) can be done in response. The scale, timing, cost and potential community acceptability of options vary hugely but at least form the basis of an informed conversation about potential responses now and into the future.

Embracing the plover lover community – learning from other jurisdictions

Amanda Blakney, Huon Valley Council

Speaker Profile

Amanda has a background in conservation management and environmental sustainability, with a special interest in shorebirds – having fallen in love them when studying the impacts of disturbance and dogs on Hooded Plovers in the Honours year of her Science degree. She currently works at Huon Valley Council as the Manager Environmental Services. Amanda is also an active BirdLife and Landcare volunteer, running childrens’ activities at events and contributing to the engagement of members and the community through a variety of means.

Abstract

Perhaps in response to the ever-crazy world that we live in, there has been a noticeable shift towards the desire for storytelling over fact-telling in recent times. This has coincided with a dramatic increase in the popularity of citizen science initiatives. Similarities can be drawn between these two trends, with both having a grounding in meaningful connection to our world. This can be in stark contrast to the traditional science philosophy of not getting attached to your subject. Fostering of empathy and community ownership is increasingly being incorporated into the communications strategies for the conservation of beach-nesting birds across Australia and Internationally. While not replacing the need for targeted compliance work entirely, the results from other areas are encouraging. This presentation will explore what Tasmania can learn from elsewhere and how those examples relate to beach-nesting birds in Tasmania. Some of the issues that beach-nesting birds face in Tasmania and best practice nest protection measures will also be presented.

Local community contributions to coastal protection in the Huon and Channel

Matt Taylor, Tasmanian Land Conservancy

Speaker Profile

Matt Taylor has worked as an ecologist with the Tasmanian Land Conservancy for the past 10 years. He is also a PhD candidate, researching the socio-ecology of wildlife conservation on private land. The project is a partnership between UTAS and TLC. He lives in the Huon with his family on a small farm near Cygnet.

Abstract

The coastal landscape surrounding the Huon Estuary and D’Entrecasteaux Channel is a hotspot for threatened species and ecological communities. Much of this landscape is privately owned, which means that landholders have an important role to play in biodiversity conservation and the protection of coastal and riparian habitats. The Tasmanian Land Conservancy is a not-for-profit environmental organisation that has been working with landholders in the Huon and Channel to protect important natural values on their properties for nearly 20 years. TLC uses a range of nature conservation mechanisms including Permanent Reserves, Conservation Covenants, the Revolving Fund, Land for Wildlife and WildTracker – a new citizen science program that has been trialled in the Huon and on Bruny. This talk will present several case studies from across this diverse region to illustrate how private landholders are contributing to great conservation outcomes in terrestrial, freshwater and coastal environments.

POSTER

Summer intrusions in Storm Bay

Dr Clothilde Langlais. CSIRO

Profile

Dr Clothilde Langlais is a physical oceanographer and modeller at CSIRO. Her research activities are dedicated to better understanding the variability of the mechanisms governing the ocean circulation and their response to change. Her experience lies in numerical modelling approaches to oceanography. After 10 years of research on large scale ocean dynamics, climate variability and change, her research now focusses on multidisciplinary coastal projects, closely related to climate impacts, adaptation and management of our coastal resources.

Abstract

The East Australian Current (EAC) mesoscale eddies transport warm nutrient-depleted sub-tropical water down the east coast of Australia to Tasmania. The extension in Tasmania peaks in February and is weakest in winter. When EAC eddies interact with the slope, warm and salty water intrusions can occur into Storm Bay. Cooler nutrient-rich sub-Antarctic water can also reach the shelf edge in summer. While we don’t know the exact nature of the interplay between these dynamical processes, it can lead to local changes in ocean temperature and biogeochemistry in Storm Bay, and impact Tasmanian microphytoplankton communities. Using 8 years of repeat glider mission in Storm Bay, 6 years of mooring data and satellite altimetry data, we investigate the interplay between bottom driven upwelling and EAC eddies in South East Tasmania. EAC filaments seem to develop along the shelf break when a large quasi-stationary anticyclonic eddy off South East Tasmania impinges on the continental slope. Every summer, this interaction results in a surface intrusion of EAC water, concomitant with a sub-surface intrusion of cold sub-Antarctic water. Using the long timeseries, we assess the characteristics and variability of these simultaneous intrusions. In particular, during the 2016 marine heat wave, two intense intrusion events occur in Storm Bay resulting in large warm and salty anomalies in the surface and large cold and relatively fresher anomalies at depth.